The application of brushless direct current (BLDC) motors in electric power steering systems, such as in car steering systems, makes it possible for a driver to produce a larger torque with less force, which greatly reduces the operator's strength. However, conventional brushless direct current motors generally include a stator with windings, a rotor having a permanent magnet, and a controller for supplying power to the stator. The stator usually includes a stator core with the windings wound therearound. The windings include m-phase windings, each phase winding having a plurality of parallel branch circuits. When one of the branch circuits of the windings breaks, it causes unbalance between the breaking winding and the other phases of windings, thus resulting in large fluctuation of motor torque and motor vibration. Especially when the BLDC motor of the steering wheel electric power steering system fails, if the driver rotates the steering wheel, it may cause short-circuit of winding coils and produce a short-circuit current and, as a result, a braking torque is produced, which prevents rotation of the steering wheel. Therefore, the conventional BLDC motor has serious safety concerns.